This application incorporates by reference Taiwanese application Ser. No. 89115648, filed Aug. 3, 2000.
1. Field of the Invention
The invention relates in general to a control circuit for connecting a chipset and a Dual In-line Memory Module (DIMM), and more particularly to a control circuit to allow the use of an unbuffered DIMM in a system with a registered-DIMM-only chipset.
2. Description of the Related Art
In the personal workstation or server of a modern computer system, the main memory of the computer system generally uses memory modules with standard industrial architecture. These memory modules generally include a plurality of dynamic random access memory (DRAM) chipsets which are mounted on a small circuit board and the small circuit board is connected to a memory module socket electrically. Lately, standard industrial architecture of memory modules includes Single In-line Memory Modules (SIMMs) and DIMMs. A SIMM has memory units mounted on one side of a circuit board while a DIMM has memory units mounted on both sides of a circuit board. Nowadays, a personal computer mostly uses an unbuffered DIMM if a DIMM is selected as the main memory. However, for a computer system with higher main memory volume requirements (i.e. a server), the unregistered DIMMs are the popular choice.
In a system with a registered-DIMM-only chipset, only registered DIMMs are supported. If an unbuffered DIMM is installed in a memory module socket of the system, registered-DIMM-only chipset, it will not function normally because of differences in timing between the unbuffered and registered DIMM. Accordingly, use and selection of memory modules is not very flexible. Moreover, cost of a registered DIMM is higher than an unbuffered DIMM. If the above server system can use an unbuffered DIMM and satisfy system requirements, a reduction in the cost of the system can be realized.
It is therefore an object of the invention to provide a control circuit for a user to not only use a registered DIMM but also an unbuffered DIMM in a system with a registered-DIMM-only chipset. In this way, the user can selectively use either a registered or an unbuffered DIMM according to actual condition. The invention can also contribute to reduce the cost of the system.
The invention achieves the above-identified objects by providing a control circuit to allow the use of an unbuffered dual in-line memory module (DIMM) in a system with a registered-DIMM-only chipset. The control circuit is for receiving a first address signal and first control signal outputted from the registered-DIMM-only chipset and receiving a recognizing signal for recognizing a DIMM, wherein the DIMM is installed into a memory module socket. The control circuit includes a buffering module and transmitting module. The buffering module is for receiving the first address signal and first control signal and then outputting a second address signal and second control signal to an address bus and a control bus which are electrically connected to the memory module socket. The buffering module further includes registers, a clock buffer and a control input terminal, which is for receiving the recognizing signal. The transmitting module is for receiving the first address signal and first control signal. The transmitting module further receives the recognizing signal to determine whether to output the first address signal and the first control signal to the address bus and control bus.
Wherein, when the installed DIMM is a registered DIMM, the recognizing signal triggers the transmitting module to output the first address signal and first control signal to the memory module socket. When the installed DIMM is an unbuffered DIMM, the recognizing signal triggers the buffering module to output the second address signal and second control signal to the memory module socket.